Combined seat and backrest unit for an office chair



FIG. 1 is a side elevational view of a combined seat and backrest unit for an office chair embodying the design;

FIG. 2 is a front elevational view of the combined seat and backrest unit for an office chair of FIG. 1;

FIG. 3 is a rear elevational view of the combined seat and backrest unit for an office chair of FIG. 1;

FIG. 4 is a side elevational view of a modified form of a combined seat and backrest unit for an office chair embodying the design;

FIG. 5 is a front elevational view of the combined seat and backrest unit for an office chair of FIG. 4;

FIG. 6 is a rear elevational view of the combined seat and backrest unit for an office chair of FIG. 4.

The side of the combined seat and backrest unit for an office chair that is not shown is a mirror image of the side that is shown in FIG. 1. 

The ornamental design for a combined seat and backrest unit for an office chair, as shown and described. 